Colorimetric Sensor based on Plasmonic Nanoparticles for the Determination of Salicylic Acid Content in a Fruit Sample

Salicylic acid (SA) is a signaling molecule that plays an important role in the regulation of many physiological processes in various plants and is one of the organic micromolecular compounds widely used in the pharmaceutical and chemical industries. In this research, a colorimetric salicylic acid sensor based on gold nanoparticles (AuNPs), a plasmonic nanoparticle, was developed. The plasmon resonance absorption band of AuNPs at 525.5 nm was used for the detection of SA. The pH and AuNPs concentration were optimized to find the suitable operating conditions. Under optimum conditions, the linear working range of the AuNPs-based colorimetric sensor is 7.5–100.0 µM with a detection limit of 0.86 µM. The colorimetric sensor exhibits good selectivity and stability. The analytical applicability of the AuNPs-based colorimetric sensor was investigated by determining the SA content in orange.